Agree with all you said, Mike.
Great product to manufacture and sell if your customers can't tell what it does for them.
I suspect all car engine temps move up and down since most use the same basic kind of tstat ... most simply don't have coolant temp gages.
1991 350 SDL (200K and she ain't bent, yet)
former 2002 E320 4Matic Wagon - good car
former 1985 300 CD - great car
former 1981 300 TD - good car
former 1972 280 SEL - not so good car
a couple of those diesel Rabbits ...40-45 mpg